Poly(amide-imide) and method of preparing the same

ABSTRACT

A poly(amide-imide) is provided. The poly(amide-imide) is represented by formula (1),wherein R is a C6 aryl group, a C7-C8 aralkyl group, a C2-C6 alkoxyalkyl group, or a C3-C18 alkyl group; and 0.02≤X≤0.5.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of and claims thepriority benefit of a prior application Ser. No. 16/283,832, filed onFeb. 25, 2019. The prior application Ser. No. 16/283,832 claims thepriority benefit of Taiwan application serial no. 107129002, filed onAug. 20, 2018. The entirety of each of the above-mentioned patentapplications is hereby incorporated by reference herein and made a partof this specification.

BACKGROUND 1. Field of the Invention

This disclosure is related to a polymer, and in particular to apoly(amide-imide) and a preparation method thereof.

2. Description of Related Art

Many thermoplastic resins called “engineering plastics” have been widelyused in various fields due to their excellent heat resistance, chemicalresistance, flame retardance and the like. However, there are stilllimitations in the use of engineering plastics. For example, theprocessing temperature of polyetherimide is quite high (between 350° C.and 380° C.), which is not easy to achieve for a general machine.Further, when polyvinylidenefluoride is subjected to high-temperaturemolding, if the processing temperature is 320° C. or more, hydrofluoricacid having strong corrosive properties is likely to be generated.Therefore, how to improve the applicability of engineering plastics isstill an important topic for active research at present.

SUMMARY

The present invention provides a poly(amide-imide) having a good meltprocessability by reduced melt processing temperature, and a process forpreparing the same.

In this invention, the poly(amide-imide) is represented by formula (1)below.

In formula (1), R is a C₆ aryl group, a C₇-C₈ aralkyl group, a C₂-C₆alkoxyalkyl group, or a C₃-C₁₈ alkyl group, and 0.02≤X≤0.5.

In some embodiments of this invention, R is selected from the functionalgroups represented by formula (a) to formula (g) shown below,

and * represents a bonding position in formula (a) to formula (g).

In some embodiments of this invention, the weight-average molecularweight of the poly(amide-imide) is between 47,000 g/mol and 55,000g/mol.

In this invention, a preparation method of a poly(amide-imide) comprisesthe following steps. A first solution containing a poly(amide-imide) isformed by reacting a modifier with a polyimide dissolved in a solvent.The poly(amide-imide) is precipitated from the first solution by addinga non-solvent into the first solution containing the poly(amide-imide).The polyimide comprises a repeat unit represented by formula (I). Themodifier is represented by formula (II). The poly(amide-imide) isrepresented by formula (1).

The weight-average molecular weight of the polyimide is between 44,000g/mol and 50,000 g/mol. In formula (1), R is a C₆ aryl group, a C₇-C₈aralkyl group, a C₂-C₆ alkoxyalkyl group, or a C₃-C₁₈ alkyl group, and0.02≤X≤0.5.

In some embodiments of this invention, R is selected from the functionalgroups represented by formula (a) to formula (g) shown below,

and * represents a bonding position in formula (a) to formula (g).

In some embodiments of this invention, the weight-average molecularweight of the poly(amide-imide) is between 47,000 g/mol and 55,000g/mol.

In some embodiments of this invention, the solvent comprisesN,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP) ortetrahydrofuran (THF).

In some embodiments of this invention, the non-solvent comprisesmethanol, ethanol, isopropanol, or water.

In some embodiments of this invention, the method further comprisesusing a diluent to dilute the first solution containing thepoly(amide-imide) to form a second solution containing thepoly(amide-imide) before adding the non-solvent to the first solutioncontaining the poly(amide-imide).

In some embodiments of this invention, a viscosity of the first solutioncontaining the poly(amide-imide) is between 1,000 cps and 10,000 cps,and a viscosity of the second solution containing the poly(amide-imide)is between 10 cps and 200 cps.

In some embodiments of this invention, a ratio of the weight-averagemolecular weight of the poly(amide-imide) and the weight-averagemolecular weight of the polyimide is between 2.2 and 2.6.

In some embodiments of this invention, a reaction temperature of areaction between the polyimide and the modifier is between 30° C. and100° C.

Based on the above, the method of preparing the poly(amide-imide) of thepresent invention comprises the following steps. The modifierrepresented by the above formula (II) is reacted with the polyimiderepresented by the above formula (I) to form a solution containing apoly(amide-imide), and then a non-solvent is added to the solution.Thereby, the poly(amide-imide) represented by the above formula (1) canbe obtained. Further, based on the structure shown in formula (1), it isunderstood that the poly(amide-imide) of the present invention has aring-opening structure to increase the free volume of molecules, wherebythe poly(amide-imide) has good melt processability by reduced meltprocessing temperature.

The above described features and advantages of the present inventionwill be more apparent from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic flow chart of a method for preparing apoly(amide-imide) according to an embodiment of the present invention.

FIG. 2 is a schematic flow chart of a method for preparing apoly(amide-imide) according to another embodiment of the presentinvention.

DESCRIPTION OF THE EMBODIMENTS

In the present specification, a range represented by “a numerical valueto another numerical value” is a schematic representation for avoidinglisting all of the numerical values in the range in the specification.Therefore, the recitation of a specific numerical range covers anynumerical value in the numerical range and a smaller numerical rangedefined by any numerical value in the numerical range, as is the casewith the any numerical value and the smaller numerical range statedexplicitly in the specification.

In the present specification, skeleton formulas are sometimes used torepresent the structures of polymers or groups. Such representation canomit carbon atoms, hydrogen atoms, and carbon-hydrogen bonds. Of course,structural formulas with clear illustrations of atoms or atomic groupsare definitive.

As used herein, “about,” “approximate,” “essentially,” or“substantially” includes the values and average values within acceptabledeviations of the particular values determined by those of ordinaryskill in the art, and considers the specific amount of measurement anderror associated with the measurement (i.e., the limitations of themeasurement system). For example, “about” can mean within one or morestandard deviations of the value, or within ±30%, ±20%, ±15%, ±10%, ±5%,for example. Furthermore, the terms “about”, “approximate”,“essentially”, or “substantially” used herein may select a moreacceptable range or standard deviation depending on the nature of themeasurement or other properties, but all properties can be appliedwithout specifying a standard deviation.

In order to provide a poly(amide-imide) with good melt processability byreduced melt processing temperature, the present invention provides amethod for preparing a poly(amide-imide). The obtained poly(amide-imide)can attain the above advantage. Hereinafter, the specific embodimentsare described as examples to illustrate that the present invention canbe implemented.

FIG. 1 is a schematic flow chart of a method for preparing apoly(amide-imide) according to an embodiment of the present invention.Referring to FIG. 1 , first, in step S10, a modifier is reacted with apolyimide dissolved in a solvent to form a solution containing thepoly(amide-imide). That is, in the present embodiment, thepoly(amide-imide) is obtained by modifying the polyimide with themodifier.

In this embodiment, the polyimide comprises a repeat unit represented byformula (I) of

That is, in the present embodiment, the dianhydride monomer used tomanufacture the polyimide includes4,4′-(4,4′-isopropylidenediphenoxy)bis(phthalic anhydride) (BPADA), andthe diamine monomer used to manufacture the polyimide includesm-phenylenediamine (m-PDA). In the present embodiment, the polyimide maybe a commercially available product or a recycled polyimide powder(i.e., a secondary material), wherein the commercial product is, forexample, ULTEM 9011 spinning grade PEI and ULTEM 1010 PEI manufacturedby Sabic Industries. In this embodiment, the weight-average molecularweight of the polyimide is between about 44,000 g/mol and about 50,000g/mol.

The solvent is not particularly limited as long as it can dissolve theaforementioned polyimide. In this embodiment, the solvent may includeN,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), ortetrahydrofuran (THF). Further, in the present embodiment, aconcentration of the aforementioned polyimide in the solvent may bebetween about 5 wt % and about 40 wt %.

In this embodiment, the modifier may be represented by formula (II) ofNH₂R. In formula (II), R may be a C₆ aryl group, a C₇-C₈ aralkyl group,a C₂-C₆ alkoxyalkyl group, or a C₃-C₁₈ alkyl group. In this embodiment,R may be selected from the functional groups represented by formula (a)to formula (g) shown below,

and in formula (a) to formula (g), * represents a bonding positionthereof. That is, in the present embodiment, the modifier may beaniline, phenylmethylamine, phenethylamine, 3-isopropoxypropylamine(IPOPA), isopropylamine, n-butylamine, or octadecylamine. From anotherpoint of view, in the present embodiment, the modifier may be a smallmolecule amine which is liquid at room temperature and under normalpressure.

In this embodiment, the poly(amide-imide) is represented by formula (1)of

In formula (1), the definition of R is the same as the definition of Rin formula (II) above, and 0.02≤X≤0.5. According to the structure shownin formula (1), in this embodiment, the modifier is reacted with theimide group of the polyimide to open the imide group ring of thepolyimide. That is, in the present embodiment, the poly(amide-imide)represented by formula (1) is a side-chain modified poly(amide-imide).In this embodiment, in the reaction of the polyimide and the modifier,the reaction temperature is between about 30° C. and about 100° C., andthe reaction time is between about 4 hours and about 8 hours.

In this embodiment, a weight-average molecular weight of thepoly(amide-imide) is between about 47,000 g/mol and about 55,000 g/mol.Moreover, in this embodiment, the ratio of the weight-average molecularweight of the poly(amide-imide) to the weight-average molecular weightof the polyimide is between about 2.2 and about 2.6. In this embodiment,the solution containing the aforementioned poly(amide-imide) has aviscosity of between about 1,000 cps and about 10,000 cps.

Next, referring to FIG. 1 , in step S12, a non-solvent is added to thesolution containing the poly(amide-imide) to precipitate thepoly(amide-imide) from the solution. In detail, after the non-solvent isadded to the solution containing the poly(amide-imide), the solvent ofthe poly(amide-imide) solution will be replaced by the non-solvent toprecipitate solids of the poly(amide-imide). In this embodiment, thenon-solvent may include methanol, ethanol, isopropanol or water. In thisembodiment, the poly(amide-imide) precipitated from the solution is inthe form of a solid powder.

After performing the above steps S10 to S12, the poly(amide-imide)provided in one embodiment of this invention may be prepared. In thisembodiment, the poly(amide-imide) is represented by formula (1) shown inthe foregoing, wherein the definitions of R and X have been described indetail above, and thus will not be described herein again. In addition,the related description of the poly(amide-imide) has been described indetail in the foregoing, and thus will not be described herein again.

It is to be noted that, in this embodiment, the modifier represented bythe above formula (II) and the polyimide represented by the aboveformula (I) are reacted to form a solution containing thepoly(amide-imide), and the non-solvent is then added to the solution,whereby the poly(amide-imide) represented by the above formula (1) canbe obtained. Further, based on the structure shown in formula (1), it isknown that due to the ring-opening structure (i.e. a sidechain modifiedby the modifier), the free volume of molecules of the poly(amide-imide)is increased, and thus the poly(amide-imide) may have good meltprocessability by reduced melt processing temperatures.

Further, in the embodiment shown in FIG. 1 , the poly(amide-imide) isprepared by performing steps S10 to S12, but this invention is notlimited thereto. Hereinafter, other embodiments will be described withreference to FIG. 2 . It is to be noted that the following embodimentshave used the same or similar elements, and the same or similar elementsare denoted the same or similar numerals, and the description of thesame technical content is omitted. For the description of the omittedportions, reference may be made to the foregoing embodiments, and is notrepeated in the following embodiments.

FIG. 2 is a schematic flow chart of a method for preparing apoly(amide-imide) according to another embodiment of this invention.Referring to FIG. 2 and FIG. 1 simultaneously, the preparation methodshown in FIG. 2 is similar to the preparation method shown in FIG. 1 ,and therefore the same or similar steps are denoted by the same orsimilar numerals, and the description of the same technical contents isthus omitted. For the description of the omitted portions, reference maybe made to the foregoing embodiments. Hereinafter, the differencebetween the preparation method shown in FIG. 2 and the preparationmethod shown in FIG. 1 will be explained.

Referring to FIG. 2 , before the step S12, the preparation method ofthis embodiment includes performing the step S20 to dilute the solutioncontaining the poly(amide-imide) represented by the above formula (1)with a diluent to form a diluted solution containing the foregoingpoly(amide-imide).

The diluent is not particularly limited as long as it can dissolve theaforementioned poly(amide-imide). In this embodiment, the diluent mayinclude N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), ortetrahydrofuran (THF).

In this embodiment, a viscosity of the solution containing thepoly(amide-imide) before dilution is between about 1,000 cps and about10,000 cps, and a viscosity of the diluted solution containing thepoly(amide-imide) is about 10 cps to about 200 cps.

Features of this invention will be more specifically described belowwith reference to Examples 1-14 and Comparative Example 1. Although thefollowing examples are described, the materials used, their amounts andratios, processing details, processing flows, and the like can beappropriately changed without departing from the scope of the invention.Therefore, the invention should not be construed restrictively by theexamples described below.

Example 1

First, 100 parts by weight of polyimide (manufactured by Sabic, tradename: ULTEM 1010 PEI) was dissolved in a solvent DMAc to form a 25 wt %polyimide solution. Next, 5 parts by weight of a modifier aniline wasadded to the polyimide solution, and the reaction of the modifieraniline and the polyimide was carried out at 80° C. for 6 hours to forma solution containing the poly(amide-imide) of Example 1, wherein amolar ratio of the polyimide and the modifier aniline was 1:25.7, andthe solution containing the poly(amide-imide) of Example 1 had aviscosity of about 10,000 cps. Subsequently, the solution containing thepoly(amide-imide) of Example 1 was diluted with a diluent DMAc to form adiluted solution containing the poly(amide-imide) of Example 1 andhaving a viscosity of about 100 cps. Next, 2 liters (or an excessamount) of non-solvent methanol was added to the diluted solution toprecipitate the poly(amide-imide) of Example 1. It is worth noting thatthe precipitated poly(amide-imide) of Example 1 was subjected tofiltering and drying steps for subsequent use.

Example 2

First, 100 parts by weight of polyimide (manufactured by Sabic, tradename: ULTEM 1010 PEI) was dissolved in a solvent DMAc to form a 25 wt %polyimide solution. Next, 1.5 parts by weight of a modifierphenylmethylamine was added to the polyimide solution, and the reactionof the modifier phenylmethylamine and the polyimide was carried out at80° C. for 6 hours to form a solution containing the poly(amide-imide)of Example 2, wherein the molar ratio of the polyimide to the modifierphenylmethylamine was 1:6.7, and a viscosity of the solution containingthe poly(amide-imide) of Example 2 was about 7,300 cps. Subsequently,the solution containing the poly(amide-imide) of Example 2 was dilutedwith a diluent DMAc to form a diluted solution containing thepoly(amide-imide) of Example 2 and having a viscosity of about 100 cps.Thereafter, 2 liters (or an excess amount) of non-solvent methanol wasadded to the diluted solution to precipitate the poly(amide-imide) ofExample 2. It is worth noting that the precipitated poly(amide-imide) ofExample 2 is subjected to filtering and drying steps for subsequent use.

Example 3

First, 100 parts by weight of polyimide (manufactured by Sabic, tradename: ULTEM 1010 PEI) was dissolved in a solvent DMAc to form a 25 wt %polyimide solution. Next, 2 parts by weight of a modifierphenylmethylamine was added to the polyimide solution, and the reactionof the modifier phenylmethylamine and the polyimide was carried out at80° C. for 6 hours to form a solution containing the poly(amide-imide)of Example 3, wherein the molar ratio of the polyimide to the modifierphenylmethylamine was 1:8.9, and a viscosity of the solution containingthe poly(amide-imide) of Example 3 was about 4,400 cps. Subsequently,the solution containing the poly(amide-imide) of Example 3 was dilutedwith a diluent DMAc to form a diluted solution containing thepoly(amide-imide) of Example 3, wherein a viscosity of the dilutedsolution was about 100 cps. Thereafter, 2 liters (or an excess amount)of non-solvent methanol was added to the diluted solution to precipitatethe poly(amide-imide) of Example 3. It is worth noting that theprecipitated poly(amide-imide) of Example 3 is subjected to filteringand drying steps for subsequent use.

Example 4

First, 100 parts by weight of polyimide (manufactured by Sabic, tradename: ULTEM 1010 PEI) was dissolved in a solvent DMAc to form a 25 wt %polyimide solution. Next, 5 parts by weight of a modifier phenethylaminewas added to the polyimide solution, and the reaction of the modifierphenethylamine and the polyimide was carried out at 80° C. for 6 hoursto form a solution containing the poly(amide-imide) of Example 4,wherein the molar ratio of the polyimide to the modifier phenethylaminewas 1:19.8, and a viscosity of the solution containing thepoly(amide-imide) of Example 4 was about 1,000 cps. Subsequently, thesolution containing the poly(amide-imide) of Example 4 was diluted witha diluent DMAc to form a diluted solution containing thepoly(amide-imide) of Example 4, wherein a viscosity of the dilutedsolution was about 100 cps. Thereafter, 2 liters (or an excess amount)of non-solvent methanol was added to the diluted solution to precipitatethe poly(amide-imide) of Example 4. It is worth noting that theprecipitated poly(amide-imide) of Example 4 is subjected to filteringand drying steps for subsequent use.

Example 5

First, 100 parts by weight of polyimide (manufactured by Sabic, tradename: ULTEM 1010 PEI) was dissolved in a solvent DMAc to form a 25 wt %polyimide solution. Next, 1.1 parts by weight of a modifier3-isopropoxypropylamine was added to the polyimide solution, and thereaction of the modifier 3-isopropoxypropylamine and the polyimide wascarried out at 80° C. for 6 hours to form a solution containing thepoly(amide-imide) of Example 5. The molar ratio of the polyimide and themodifier 3-isopropoxypropylamine was 1:4.5, and a viscosity of thesolution containing the poly(amide-imide) of Example 5 was about 9,300cps. Subsequently, the solution containing the poly(amide-imide) ofExample 5 was diluted with a diluent DMAc to form a diluted solutioncontaining the poly(amide-imide) of Example 5, wherein a viscosity ofthe diluted solution was about 100 cps. Thereafter, 2 liters (or anexcess amount) of non-solvent methanol was added to the diluted solutionto precipitate the poly(amide-imide) of Example 5. It is worth notingthat the precipitated poly(amide-imide) of Example 5 is subjected tofiltering and drying steps for subsequent use.

Example 6

First, 100 parts by weight of polyimide (manufactured by Sabic, tradename: ULTEM 1010 PEI) was dissolved in a solvent DMAc to form a 25 wt %polyimide solution. Next, 2 parts by weight of a modifier3-isopropoxypropylamine was added to the polyimide solution, and thereaction of the modifier 3-isopropoxypropylamine and the polyimide wascarried out at 80° C. for 6 hours to form a solution containing thepoly(amide-imide) of Example 6. The molar ratio of the polyimide and themodifier 3-isopropoxypropylamine was 1:8.2, and a viscosity of thesolution containing the poly(amide-imide) of Example 6 was about 7,800cps. Subsequently, the solution containing the poly(amide-imide) ofExample 6 was diluted with a diluent DMAc to form a diluted solutioncontaining the poly(amide-imide) of Example 6, wherein a viscosity ofthe diluted solution was about 100 cps. Thereafter, 2 liters (or anexcess amount) of non-solvent methanol was added to the diluted solutionto precipitate the poly(amide-imide) of Example 6. It is worth notingthat the precipitated poly(amide-imide) of Example 6 is subjected tofiltering and drying steps for subsequent use.

Example 7

First, 100 parts by weight of polyimide (manufactured by Sabic, tradename: ULTEM 1010 PEI) was dissolved in a solvent DMAc to form a 25 wt %polyimide solution. Next, 5 parts by weight of a modifier3-isopropoxypropylamine was added to the polyimide solution, and thereaction of the modifier 3-isopropoxypropylamine and the polyimide wascarried out at 80° C. for 6 hours to form a solution containing thepoly(amide-imide) of Example 7. The molar ratio of the polyimide and themodifier 3-isopropoxypropylamine was 1:20.5, and a viscosity of thesolution containing the poly(amide-imide) of Example 7 was about 2,000cps. Subsequently, the solution containing the poly(amide-imide) ofExample 7 was diluted with a diluent DMAc to form a diluted solutioncontaining the poly(amide-imide) of Example 7, wherein the viscosity ofthe diluted solution was about 100 cps. Thereafter, 2 liters (or anexcess amount) of non-solvent methanol was added to the diluted solutionto precipitate the poly(amide-imide) of Example 7. It is worth notingthat the precipitated poly(amide-imide) of Example 7 is subjected tofiltering and drying steps for subsequent use.

Example 8

First, 100 parts by weight of polyimide (manufactured by Sabic, tradename: ULTEM 1010 PEI) was dissolved in a solvent DMAc to form a 25 wt %polyimide solution. Next, 1.1 parts by weight of a modifier n-butylaminewas added to the polyimide solution, and the reaction of the modifiern-butylamine and the polyimide was carried out at 80° C. for 6 hours toform a solution containing the poly(amide-imide) of Example 8, whereinthe molar ratio of the polyimide to the modifier n-butylamine was 1:7.2,and a viscosity of the solution containing the poly(amide-imide) ofExample 8 was about 8,500 cps. Subsequently, the solution containing thepoly(amide-imide) of Example 8 was diluted with a diluent DMAc to form adiluted solution containing the poly(amide-imide) of Example 8, whereina viscosity of the diluted solution was about 100 cps. Thereafter, 2liters (or an excess amount) of non-solvent methanol was added to thediluted solution to precipitate the poly(amide-imide) of Example 8. Itis worth noting that the precipitated poly(amide-imide) of Example 8 issubjected to filtering and drying steps for subsequent use.

Example 9

First, 100 parts by weight of polyimide (manufactured by Sabic, tradename: ULTEM 1010 PEI) was dissolved in a solvent DMAc to form a 25 wt %polyimide solution. Next, 2 parts by weight of a modifier n-butylaminewas added to the polyimide solution, and the reaction of the modifiern-butylamine and the polyimide was carried out at 80° C. for 6 hours toform a solution containing the poly(amide-imide) of Example 9, whereinthe molar ratio of the polyimide to the modifier n-butylamine was1:13.1, and a viscosity of the solution containing the poly(amide-imide)of Example 9 was about 6900 cps. Subsequently, the solution containingthe poly(amide-imide) of Example 9 was diluted with a diluent DMAc toform a diluted solution containing the poly(amide-imide) of Example 9,wherein a viscosity of the diluted solution was about 100 cps.Thereafter, 2 liters (or an excess amount) of non-solvent methanol wasadded to the diluted solution to precipitate the poly(amide-imide) ofExample 9. It is worth noting that the precipitated poly(amide-imide) ofExample 9 is subjected to filtering and drying steps for subsequent use.

Example 10

First, 100 parts by weight of polyimide (manufactured by Sabic, tradename: ULTEM 1010 PEI) was dissolved in a solvent DMAc to form a 25 wt %polyimide solution. Next, 5 parts by weight of a modifier n-butylaminewas added to the polyimide solution, and the reaction of the modifiern-butylamine and the polyimide was carried out at 80° C. for 6 hours toform a solution containing the poly(amide-imide) of Example 10. Themolar ratio of the polyimide to the modifier n-butylamine was 1:32.8,and a viscosity of the solution containing the poly(amide-imide) ofExample 10 was about 3,000 cps. Subsequently, the solution containingthe poly(amide-imide) of Example 10 was diluted with a diluent DMAc toform a diluted solution containing the poly(amide-imide) of Example 10,wherein the diluted solution had a viscosity of about 100 cps.Thereafter, 2 liters (or an excess amount) of non-solvent methanol wasadded to the diluted solution to precipitate the poly(amide-imide) ofExample 10. It is worth noting that the precipitated poly(amide-imide)of Example 10 is subjected to filtering and drying steps for subsequentuse.

Example 11

First, 100 parts by weight of polyimide (manufactured by Sabic, tradename: ULTEM 1010 PEI) was dissolved in a solvent DMAc to form a 25 wt %polyimide solution. Next, 2 parts by weight of a modifier isopropylaminewas added to the polyimide solution, and the reaction of the modifierisopropylamine and the polyimide was carried out at 80° C. for 6 hoursto form a solution containing the poly(amide-imide) of Example 11. Themolar ratio of the polyimide to the modifier isopropylamine was 1:16.2,and a viscosity of the solution containing the poly(amide-imide) ofExample 11 was about 4,410 cps. Subsequently, the solution containingthe poly(amide-imide) of Example 11 was diluted with a diluent DMAc toform a diluted solution containing the poly(amide-imide) of Example 11,wherein a viscosity of the diluted solution was about 100 cps.Thereafter, 2 liters (or an excess amount) of non-solvent methanol wasadded to the diluted solution to precipitate the poly(amide-imide) ofExample 11. It is worth noting that the precipitated poly(amide-imide)of Example 11 is subjected to filtering and drying steps for subsequentuse.

Example 12

First, 100 parts by weight of polyimide (manufactured by Sabic, tradename: ULTEM 1010 PEI) was dissolved in a solvent DMAc to form a 25 wt %polyimide solution. Next, 5 parts by weight of a modifier isopropylaminewas added to the polyimide solution, and the reaction of the modifierisopropylamine and the polyimide was carried out at 80° C. for 6 hoursto form a solution containing the poly(amide-imide) of Example 12. Themolar ratio of the polyimide to the modifier isopropylamine was 1:40.6,and a viscosity of the solution containing the poly(amide-imide) ofExample 12 was about 3,500 cps. Subsequently, the solution containingthe poly(amide-imide) of Example 12 was diluted with a diluent DMAc toform a diluted solution containing the poly(amide-imide) of Example 12,wherein a viscosity of the diluted solution was about 100 cps.Thereafter, 2 liters (or an excess amount) of non-solvent methanol wasadded to the diluted solution to precipitate the poly(amide-imide) ofExample 12. It is noteworthy that the precipitated poly(amide-imide) ofExample 12 is subjected to filtering and drying steps for subsequentuse.

Example 13

First, 100 parts by weight of polyimide (manufactured by Sabic, tradename: ULTEM 1010 PEI) was dissolved in a solvent DMAc to form a 25 wt %polyimide solution. Next, 1 part by weight of a modifier octadecylaminewas added to the polyimide solution, and the reaction of the modifieroctadecylamine and the polyimide was carried out at 80° C. for 6 hoursto form a solution containing the poly(amide-imide) of Example 13. Themolar ratio of the polyimide to the modifier octadecylamine was 1:1.8,and the solution containing the poly(amide-imide) of Example 13 had aviscosity of about 9,000 cps. Next, the solution containing thepoly(amide-imide) of Example 13 was diluted with a diluent DMAc to forma diluted solution containing the poly(amide-imide) of Example 13,wherein a viscosity of the diluted solution was about 100 cps.Thereafter, 2 liters (or an excess amount) of non-solvent methanol wasadded to the diluted solution to precipitate the poly(amide-imide) ofExample 13. It is noteworthy that the precipitated poly(amide-imide) ofExample 13 is subjected to filtering and drying steps for subsequentuse.

Example 14

First, 100 parts by weight of polyimide (manufactured by Sabic, tradename: ULTEM 1010 PEI) was dissolved in a solvent DMAc to form a 25 wt %polyimide solution. Next, 2 parts by weight of a modifier octadecylaminewas added to the polyimide solution, and the reaction was carried out at80° C. for 6 hours to form a solution containing the poly(amide-imide)of Example 14. The molar ratio of the polyimide to the modifieroctadecylamine was 1:3.6, and a viscosity of the solution containing thepoly(amide-imide) of Example 14 was about 7,100 cps. Subsequently, thesolution containing the poly(amide-imide) of Example 14 was diluted witha diluent DMAc to form a diluted solution containing thepoly(amide-imide) of Example 14, wherein a viscosity of the dilutedsolution was about 100 cps. Thereafter, 2 liters (or an excess amount)of non-solvent methanol was added to the diluted solution to precipitatethe poly(amide-imide) of Example 14. It is noteworthy that theprecipitated poly(amide-imide) of Example 14 is subjected to filteringand drying steps for subsequent use.

Comparative Example 1

In Comparative Example 1, no modifier was used to modify polyimide(manufactured by Sabic, trade name: ULTEM 1010 PEI). That is, thepolyimide of commercially available ULTEM 1010 PEI is directly used inComparative Example 1.

Thereafter, measurements of the glass transition temperature (Tg), the10% thermogravimetric loss temperature (T_(d10%)), the viscosity(η_(inh)), the melt flow index (MI) and contact angles of thepoly(amide-imide)s of Examples 1-14 and the ULTEM 1010 PEI ofComparative Example 1 were respectively performed. The description ofthe aforementioned measurements is made as follows, and the measurementresults are shown in Table 1.

<Measurement of Glass Transition Temperature (Tg)>

The glass transition temperatures (° C.) of the poly(amide-imide)s ofExamples 1-14 and the ULTEM 1010 PEI of Comparative Example 1 weremeasured under a nitrogen atmosphere and a heating rate of 10° C./min bya thermomechanical analyzer (manufactured by Maia Co., Ltd., model:DSC200 F3).

<Measurement of 10% Thermogravimetric Loss Temperature (T_(d10%))>

The weight changes of the poly(amide-imide)s of Examples 1-14 and theULTEM 1010 PEI of Comparative Example 1 were respectively measured andrecorded under a nitrogen atmosphere and a heating rate of 20° C./min bya thermogravimetric analyzer (manufactured by TA Instruments, Model:Q50). The temperature measured for each one of the poly(amide-imide)sand ULTEM 1010 PEI at a weight loss of 10% is the 10% thermogravimetricloss temperature (° C.).

<Measurement of Viscosity (η_(inh))>

The poly(amide-imide)s of Examples 1-14 and the ULTEM 1010 PEI ofComparative Example 1 were respectively dissolved in a solvent DMAc toform a solution having a concentration of 0.5 g/dL, and the viscosity(dL/g) of each solution was measured at a temperature of 30° C.

<Measurement of Melt Flow Index (MI)>

The melt flow indexes (g/10 min) of the poly(amide-imide)s of Examples1-14 and the ULTEM 1010 PEI of Comparative Example 1 were measuredaccording to the specifications of ASTM D-1238, and the loaded weightwas 5 Kg. The test temperature varies depending on the test sample used.For detailed test temperatures, please refer to Table 1. In general, thehigher the melt flow index is, the better melt processability is.

<Measurement of Contact Angle>

Water was dropped on the poly(amide-imide)s of Examples 1-14 and theULTEM 1010 PEI of Comparative Example 1. After water was no longerflowing, the contact angle (degree) between water and each one of thepoly(amide-imide)s and ULTEM 1010 PEI was measured using a contact anglemeasuring device (Model: Model TK-C1380U, manufactured by JVCCorporation).

TABLE 1 MI contact Tg η_(inh) (g/10 min)/test angle (° C.) T_(d10%)(°C.) (dL/g) temperature (° C.) (degree) Example 1 212 510 0.281 68/325 71Example 2 199 501 0.310 71/295 70 Example 3 193 505 0.294 66/277 67Example 4 155 493 0.291 56/240 65 Example 5 206 503 0.312 61/310 72Example 6 188 488 0.304 55/300 70 Example 7 160 458 0.301 57/240 66Example 8 199 501 0.312 82/287 71 Example 9 186 493 0.294 58/257 70Example 10 149 478 0.291 80/240 68 Example 11 202 506 0.309 63/317 67Example 12 180 471 0.298 59/295 65 Example 13 210 500 0.303  8/320 67Example 14 200 482 0.294 60/300 66 Comparative 214 528 0.314 13/337 92Example 1

As can be seen from the above Table 1, the poly(amide-imide)s ofExamples 1-14 and the ULTEM 1010 PEI of Comparative Example 1 hadsimilar glass transition temperatures and similar 10% thermogravimetricloss temperatures. The results show that the poly(amide-imide)s ofExamples 1-14 and the unmodified polyimide had similar thermalproperties, wherein the poly(amide-imide)s are represented by the aboveformula (1) and obtained by modifying the polyimide represented by theabove formula (I) by the modifier represented by the above formula (II).

As apparent from the Table 1 above, the poly(amide-imide)s of Examples1-14 and the ULTEM 1010 PEI of Comparative Example 1 had similarviscosities. This result shows that the modification process with themodifier represented by the above formula (II) does not influence thepolymerization degree of the product, i.e. the poly(amide-imide)represented by the above formula (1).

As can be seen from Table 1 above, comparing with the melt flow indexand melt processing temperature of the unmodified ULTEM 1010 PEI ofComparative Example 1, the poly(amide-imide)s of Examples 1-14 havebetter melt processability at a lower melt processing temperature. Thisresult shows that the poly(amide-imide) represented by the above formula(1) obtained by modifying the polyimide represented by the above formula(I) by the modifier represented by the above formula (II) of thisinvention has good melt processability by reduced melt processingtemperature.

As can be seen from the above Table 1, the poly(amide-imide)s ofExamples 1-14 had a lower contact angle than the contact angle of theunmodified ULTEM 1010 PEI of Comparative Example 1. This result showsthat the poly(amide-imide) represented by formula (1) obtained by usingthe modifier represented by the above formula (II) to modify thepolyimide represented by the above formula (I) was more hydrophilic,comparing with the unmodified polyimide.

Although this invention has been disclosed in the above examples, it isnot intended to limit the invention, and those skilled in the art canmake some modifications and refinements without departing from thespirit and scope of the invention. The scope of the invention is definedby the scope of the appended claims.

What is claimed is:
 1. A poly(amide-imide) represented by formula (1),

wherein R is selected from the functional group represented by formula(d) shown below,

and * represents a bonding position in formula (d), and 0.02≤X≤0.5. 2.The poly(amide-imide) of claim 1, wherein a weight-average molecularweight of the poly(amide-imide) is between 47,000 g/mol and 55,000g/mol.